1. Field of the Invention
This invention relates generally to hearing protective devices and is more specifically directed to an earplug construction useful as a hearing protector.
2. Brief Discussion of the Prior Art
Environmental sounds are typically comprised of a mixture of various sound wave frequencies having varying intensities. It is well documented that repeated or prolonged exposure to sounds of sufficiently high sound pressure level will cause temporary or permanent hearing loss. For example, exposure to sound waves of some frequencies and of varying intensities under conditions of severe impact can damage the auditory organ and cause serious hearing problems, including deafness. Injurious noises such as those caused by explosions or bursts are often comprised of a mixture of sound wave frequencies of varying intensity. These disturbing frequencies are in both the high and low frequency bands and have an intensity sufficient to cause hearing problems. Individuals who are frequently exposed to sound having such disturbing and sometimes dangerous frequencies and intensities run the risk of incurring such injuries as hearing loss or even deafness. These individuals include workers at demolition or construction sites, operators of heavy, noisy equipment and those in active military service. Ear (i.e. hearing) protection is needed to prevent a loss in hearing acuity and the gradual decrease in the threshold of hearing resulting from extended exposures to loud noise.
Sound attenuation devices are known which specifically address this problem. These include conventional earplugs, earmuffs, and the like which function to reduce the negative effects of exposure to dangerous frequencies by limiting the entry of all sound waves into the auditory organ. Typically, pre molded earplugs were made to offer the user a simple comfortable way to protect against harmful or unwanted noise. Pre molded earplugs progressed from single flange designs fitting one size, i.e., small, medium, or large, etc. As time progressed, these pre molded earplugs improved and the earplugs included multiple flanges covering a wider range of sizes an earplug would fit and attenuate. Recently, some manufacturers have added stiffeners to their multi flanged pre molded earplugs to aid in insertion, leading to improved fit and attenuation. Conventially, these insertion tools or stem stifeners have been made in the form of tubes that fit over the flexible stem and also have been in the form of stiff cylindrical inserts placed inside the earplug stem.
The above-described drawbacks and deficiencies of the prior art are alleviated by the earplug of the present invention. The earplug includes a body having a stem channel formed therein and a stem member disposed within the stem channel. According to the present invention, the stem member is formed of a material such that insertion of the earplug in an ear of a user results in the stiffness of the stem member decreasing such that at least the portion of the stem member which is inserted into the ear becomes less stiff upon being inserted and positioned within the ear.
In one embodiment, the body includes a stalk member having multiple flange elements extending therefrom and the stem member is disposed within the stem channel formed in the stalk member. Preferably, the stalk member includes an array of at least three rearwardly directed and spaced apart flange elements, wherein the first of the flange elements extends from a nose end of the stalk member. Preferably, each of the flange elements has a generally hemispherical cross section and each of the flange elements of the array includes a skirt of relatively thin uniform thickness and is composed of a soft resilient polymeric material. The soft resilient polymeric material preferably has a Shore A Durometer hardness value of between about 10 and about 90. The flange elements of the array increase serially in diameter, starting from the nose end of the stalk member.
The stem channel preferably has a first section and a second section in a first embodiment, wherein the stem member is securely disposed within the stem channel. in a frictional manner. In the exemplary embodiment, the stem member comprises an elongated member having a first end and an opposing second end. The first end comprises a paddle portion which permits a user to easily grip the stem member for inserting the earplug into an ear canal. The second end of the stem member comprises a retaining portion to aid in retaining the stem member within the stalk member. Between the paddle portion and the ball portion, the stem member includes a tapered shaft having a varying diameter. In the illustrated embodiment, the shaft has a greater diameter closer to the paddle portion and the taper of the shaft leads to a smaller diameter at the ball portion of the stem member.
According to the present invention, the stem member is formed of a material having a glass transition in the temperature range of about 50xc2x0 F. to about 100xc2x0 F. and preferably from about 80xc2x0 F. to about 100xc2x0 F. This material preferably exhibits noticeable property changes in hardness, flexability, and elastic modulus when the temperature of the material is changed. Suitable materials having these characteristics are certain polyurethane and polyvinyl chloride based polymeric materials. These properties advantageously permit the stem member to be both stiff for pushing the earplug into the ear canal and flexible to take the bend of the ear canal after the earplug has been inserted into the ear canal. After the earplug has been inserted into the ear canal, the material of the stem member permits the stem member to soften to a relaxed state and this causes any excess pressure on the ear canal to be released or relieved.
The stem member is inserted into the stem channel so that the paddle portion extends from the end of the stalk member opposite the nose end and the tapered portion of the stem member frictionally engages the first section of the stem channel and the ball portion of the stem member frictionally engages the second section of the stem channel so that the stem member is securely disposed within the stalk member.
In another embodiment, the body comprises a foam body formed from any number of suitable foams and the body may take any number of shapes and sizes.
By employing a stem member having the previously-mentioned characteristics, the earplug of the present invention offers improved ease of insertion and improved attenuation because of the improved fit within the ear canal of the user. The above-discussed and other features of the present invention will be appreciated and understood by those skilled in the art from the following detailed description and drawings.